PENTINGNYA FOSFAT BAGI TANAMAN TEBU

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1 PENTINGNYA FOSFAT BAGI TANAMAN TEBU
Foto:smno.tebulahankering.malang.2010 1

2 P DAN TANAMAN TEBU Pengendalian P-tersedia dalam tanah sangat menentukan hasil tebu dan gula. Perkembangan akar tebu akan lambat kalau suplai P-tersedia terkendala, sehingga akan muncul gangguan dalam proses penyerapan air dan hara oleh akar tanaman. Defisiensi P banyak terjadi pada tebu-ratoon, dan gejala defisisensi semakin parah dengan bertambahnya umur tanaman. P bersifat mobil dalam tubuh tanaman, sehingga gejala defisiensi muncul pertama pada daun tua. Defisiensi P ini mengakibatkan pertumbuhan tanaman kerdil. Panjang ruas, panjang batang dan diameter batang tebu semuanya mengecil kalau terjadi defisiensi P. Mula-mula gejala defisiensi pada daun tidak tampak, kemudian daun menjadi slender dan hijau kebiruan warnanya. Warna merah dan ungu juga dapat muncul, terutama di bagian pucuk daun dan tepi daun yang terkena cahaya langsung. Akhirnya helai daun mati mulai dari ujung daun dan menjalar sepanjang tepi daun. 2

3 PEMUPUKAN FOSFAT TANAMAN TEBU
Bagi tanaman tebu ternyata hara P sangat penting untuk pertumbuhan akar, pemanjangan batang, kualitas tebu dan hasil gula. Hara P membantu serapan N oleh tanaman, ketidak-seimbangan N/P tanaman menyebabkan tanaman tebu mudah roboh dan mengganggu kualitas tebu.  Efisiensi pupuk fosfat biasanya agak rendah, karena sebagian P-tersedia dalam pupuk setelah diaplikasikan ke tanah akan diikat oleh komponen tanah menjadi bentuk P-tidak tersedia.  Untuk mengatasi kendala fiksasi fosfat oleh tanah, disarankan juga aplikasi fosfat melalui daun tebu. 3

4 KETERSEDIAAN P-TANAH: HASIL DAN KUALITAS TEBU
Ketersediaan P-tanah dan aplikasi pupuk P sangat memperbaiki pertumbuhan tebu, hasil tebu dan kualitas rendemennya. Indeks luas daun tanaman tebu dan produksi bahan kering meningkat pada aplikasi pupuk P dosis tinggi. Distribusi pertumbuhan akar tanaman tebu ke arah vertikal dan horisontal juga berhubungan erat dengan ketersediaan P-tanah. Hasil tebu maksimum sebesar 76 t/ha dicapai pada tanah yang kaya P-tersedia, sedangkan pada tanah yang miskin P-tersedia ternyata hasil tebu hanya sekitar 53 t/ha. Hasil gula pada kebun tebu yang kaya P-tersedia sebesar 12 t/ha dan pada tanah yang miskin P-tersedia sebesar 8 t/ha. Kandungan P-tersedia yang terlalu tinggi dapat menekan penyerapan Zn dan Cu oleh tanaman tebu. Kandungan P-tersedia dalam tanah yang dianggap optimum adalah mg P2O5/100 g tanah; ditinjau dari hasil tebu dan gula. Sumber: Japanese Journal of Tropical Agriculture 41 (2) 52–59 4

5 RESPON TANAMAN TEBU thd Sumber: Better Crops International
P-TANAH Produktivuitas tebu dapat ditingkatkan dnegan pemupukan P yang dikombinasikan dengan N, K, S dan Zn. Aplikasi pupuk P dosis tinggi dalam strategi pemupukan yang berimbang dapat meningkatkan hasil tebu dan hasil gula. Perbaikan ketersediaan P-tanah dapat meningkatkan hasil tebu hingga 31% lebih tinggi dibandingkan dnegan kondisi kontrol. Pendekatan pemupukan P yang lebih berimbang ternyata diperlukan untuk meningkatkan hasil tebu dan hasil gula. Aplikasi pupuk P dapat merangsang pertumbuhan akar tebu, merangsang tumbuhnya anakan , mempengaruhi pertumbuhan tebu yang dapat digiling, dan meningkatkan hasil tebu per hektar. Cukupnya status P tanaman tebu sangat diperlukan untuk akumulasi simpanan gula dalam jaringan batang tebu. Sekitar % dari pupuk P yang diaplikasikan ke tanah dapat dimanfaatkan oleh tanaman tebu dalam satu musim tanam. Sumber: Better Crops International Vol. 17, No. 1, May 2003

6 Sumber: Better Crops International
Hubungan antara dosis pupuk P dengan P-tanah ekstraks Na-bikarbonat setelah 20 hari masa inkubasi tanah. Sumber: Better Crops International Vol. 17, No. 1, May 2003 6

7 REKOMENDASI PUPUK P TANAMAN TEBU
Rekomendasi pupuk P didasarkan pada hasil analisis tanah, disesuaikan dengan kapasitas tanah untuk memfiksasi P. Pupuk P diaplikasikan dalam larikan (alur) untuk memenuhi kebutuhan P tanaman tebu dan ratoon pertama. Tujuan rekomendasi pemupukan P adalah meningkatkan kandungan P-tanah hingga mendekati 206 kg P2O5/ha, seperti contoh: P-tanah kg P2O5/ha 160 115 68 28 Dosis pupuk 46 92 137 183 7

8 ASAM HUMAT MEMPERBAIKI KETERSEDIAAN HARA DAN SERAPANNYA OLEH TANAMAN
Penggunaan asam humat bersama dengan pupuk ternyata dapat meningkatkan ketersediaan hara dalam tanah dan serapannya oleh tanaman. Aplikasi asam humat 20 kg/ha bersama dengan 100% dosis pupuk rekomendasi dapat meningkatkan ketersediaan dan serapan hara makro dan Fe, Zn. Aplikasi asam humat 0.1% melalui semprotan daun dapat emningkatkan serapan hara oleh tanaman dibandingkan dengan kontrol. Sumber: J.S.VIRGINE TENSHIA and P. SINGARAM Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore 8

9 ASAM HUMAT MENINGKATKAN KETERSEDIAAN P-TANAH
Asam humat dapat memacu proses pelarutan mineral fosfat dalam tanah secara lambat & kontinyu, sehingga ketersediaan P-tanah meningkat. Asam humat dapat memperbaiki aktivitas ensim fosfatase dalam tanah, ensim ini menghidrolisis ester-fosfat menjadi fosfat anorganik, sehingga ketersediaan P-tanah meningkat. Asam humat mereduksi kemampuan tanah memfiksasi fosfat, sehingga ketersediasan P-tanah meningkat. 9

10 MEMPERBAIKI KETERSEDIAAN HARA TANAH
ASAM HUMAT + PUPUK NPK MEMPERBAIKI KETERSEDIAAN HARA TANAH Aplikasi asam humat bersama dengan pupuk NPK meningkatkan ketersediaan unsur hara dalam tanah (Vertisol dan Alfisol) bagi tanaman. Perlakuan aplikasi terbaiki adalah 10 kg ha-1 asam humat (soil application) + 0.1% asam humat semprotan daun (dua kali) + 0.3% asam humat % NPK dosis rekomendasi. Perlakuan lain yang sama baiknya adalah aplikasi asam humat 20 kg ha-1 HA (soil application) + 100% NPK dosis rekomendasi. Sumber: Journal Acta Agronomica Hungarica Volume 52, Number 3 / November 2004 10

11 P-tanah bagi TEBU Kandungan P-tanah ekstraks air (Pw) dapat digunakan sebagai dasar rekomendasi pupuk P bagi tanaman tebu. Rekomendasi pupuk fosfat bagi tebu dosisnya berkisar 0 hingga 75 pounds P2O5 per acre; tanah-tanah yang mempunyai Pw lebih ebsar dari 6 lbs per acre tidak perlu dipupuk fosfat. Semua rekomendasi pemupukan P disusun berdasarkan hasil analisis contoh tanah yang diambil sebelum tanam. 11

12 Hubungan antara kandungan P-tanah dan hasil relatif tanaman tebu
12

13 Hubungan antara dosis pupuk P dengan hasil tebu ratoon
13

14 Dampak pengapuran pada tanah-tanah yang kaya Al dan Fe
14

15 Menjenuhi tapak-tapak sorpsi dengan anion sejenis
15

16 PELARUTAN FOSFAT Asam humat dan fulvat meningkatkan pelarutan aluminum phosphate (AlPO4) dan iron phosphate (FePO4). Jumlah P yang dilepaskan oleh HA dan FA meningkat dengan waktu. Asam humat lebih efektif melarutkan logam-fosfat dibandingkan dengan FA. Hasil pelarutan ini mengandung ortofosfat bebas dan sedikit kompleks P-asam humat. Hal ini menunjukkan bahwa asam humat berperan sebagai khelator Al dan Fe, dan membebaskan anion ortofosfat.. Pertumbuhan tanaman yang diberi AlPO4 atau FePO4 menjadi lebih baik kalau ada asam humat atau fulvat. Sumber: Communications in Soil Science and Plant Analysis. Volume 29, Issue 5 & 6, 1998, Pages 16

17 KOMPLEKS P – ASAM HUMAT Al dan Fe menjadi jembatan logam dalam pembentukan kompleks asam humat – logam – P anorganik. Bentuk P dalam asam humat ternyata tergantung pH, dimana mereka diendapkan dari ekstraks alkali. Pada tanah-tanah gambut ternyata P-anorganik lebih rendah dibandingkan dnegan P-organik. Sumber: Communications in Soil Science and Plant Analysis . Volume 28, Issue 11 & 12, 1997, Pages 17

18 ASAM HUMAT MELEPASKAN P - TERIKAT
Pembentukan Fe-fosfat dan Ca-fosfat dalam tanah terjadi pada kondisi tanah alkalin, tanah berpasir dan tanah-tanah dimana banyak hujan. Fe-phosphate dan Ca-phosphates tidak larut, sehingga fosfatnya tidak tersedia bagi tanaman. Asam humat mampu memecahkan ikatan antara P, Fe dan Ca dalam tanah, sehingga ketiga hara ini menjadi tersedia bagi tanaman. Sumber: BioLynceus, LLC Estes Park, CO & Lyons, CO 18

19 PUPUK HAYATI PK BAGI TEBU
Pupuk hayati dibuat dari batuan fosfat dan kalium yang dicampur dengan belerang yang diinokulasi dengan bakteri oksidasi Acidithiobacillus. Aplikasi pupuk hayati ini dapat mereduksi pH tanah, dan memperbaiki tanaman tebu; meningkatkan ketersediaan Ca dan Mg dalam tanah. Pupuk hayati ini sangat cocok untuk tanah-tanah yang miskin P-tersedia dan miskin K-tersedia. Sumber: World Journal of Microbiology and Biotechnology. Volume 24, Number 10, , 19

20 BATUAN FOSFAT UNTUK TEBU
Aplikasi batuan fosfat dilakukan pada saat awal tanam pertama tebu dengan dosis 125, 250, 500 P2O5 kg/ha sebagai pupuk dasar. Peningkatan hasil tebu tahun pertama terjadi pada dosis batuan fosfat lebih dari 250 kg P2O5/ha. Efek residu batuan fosfat pada tanaman tebu tahun ke dua dan ke tiga hanya terjadi pada aplikasi dengan dosis 500 P2O5 kg/ha. Aplikasi batuan fosfat ternyata cukup efektif bagi tanaman tebu tahun pertama, tetapi juga mempunyai efek residu yang bagus pada tanaman tebu tahun ke dua dan ke tiga. Sumber: Proceedings of an International Meeting, Kuala Lumpur, Malaysia, July, 2001 pp 20

21 APLIKASI FOSFAT LEWAT DAUN TEBU
Percobaan aplikasi pupuk fosfat di kebun tebu melibatkan beberapa perlakuan: Kontrol (RD) : dosis pupuk (250 kg N, 115 kg P2O5 dan 115 kg K,O) RD tanpa P2O5 (250 kg N and 115 kg K2O), RD plus aplikasi fosfat lewat daun 8 kg/ha, RD plus aplikasi fosfat lewat daun 12 kg/ha, RD plus aplikasi lewat daun Boron (1%), RD plus aplikasi lewat daun Fe dan Zn (masing-masing 0.5% ) RD plus aplikasi lewat daun Si (2%). Aplikasi fosfat lewat daun dan aplikasi unusr hara mikro lewat daun dapat meningkatkan aktivitas ensim SS: sucrose synthase dan ensim SPS: sucrose phosphate synthase . Mean commercial cane sugar content was increased with foliar application of phosphorous 8 kg/ha (14.39%), 12 kg/ha (14.56%) and 0.5% iron and zinc (14.15%) as compared to control (13.68%). Sumber: Sugar Tech . Volume 5, Number 3, 21

22 APLIKASI FOSFAT LEWAT DAUN
Aplikasi fosfat lewat daun biasanya dicampur dengan N dan unsur mikro. Asam orthofosfat ternyata sangat efektif untuk aplikasi lewat daun, dibandingkan dengan senyawa fosfat lainnya. Pupuk fosfat dapat larut yang mengandung N juga dapat diaplikasikan lewat daun dengan dosis yang lebih tinggi dari dosis asam ortofosfat. Senyawa lain yang dapat diaplikasikan lewat daun sebagai pupuk fosfat adalah tri-polyphosphate dan tetra-polyphosphate. 22

23 APLIKASI ASAM HUMAT LEWAT DAUN
Aplikasi asam humat lewat tanah dan lewat daun dapat memperbaiki produktivitas dan kualitas tanaman. Humus padatan diaplikasikan ke tanah satu bulan sebelum tanam dan asam humat cair diaplikasikan lewat daun dua kali . Dosis aplikasi humus 0, 2 dan 4 g/kg dan dosis asam humat 0, 0.1 dan 0.2%. Salinitas berpengaruh negatif terhadap pertumbuhan tanaman jagung; bobot kering tanaman menurun dan serapan hara juga menurun kecuali Na dan Mn. Aplikasi humus ke tanah meningkatkan serapan N tanaman, sedangkan aplikasi asam humat lewat daun meningkatkan serapan P, K, Mg,Na,Cu dan Zn. Sumber: Soil & Water Res., 6, 2011 (1): 21–29 23

24 Korelasi terbaik terjadi pada luas permukaan akar.
CIRI-CIRI AKAR TEBU Serapan hara N, P, K, Ca, Mg, Si dan S dipengaruhi oleh sifat-sifat akar tebu seperti bobot akar, luas permukaan akar, KTK, dan KTA. Dalam tanah dan kultur larutan, KTK dan KTA akar tebu tidak berkorelasi dengan jumlah serapan kation dan anion; hal ini mungkin disebabkan oleh karena serapan ion terjadi melalui proses aktif, bukan melalui pertukaran ion. Dalam kultur larutan, bobot akar, luas permukaan akar, KTK dan KTA-akar tanaman tebu berkorelasi dengan bobot batang dan serapan hara N, K, Ca, Mg dan S. Korelasi terbaik terjadi pada luas permukaan akar. Dalam kultur tanah, hanya bobot akar yang berkorelasi erat dengan bobot batang dan serapan hara N, Mg dan S. SUmber: Journal of the Science of Food and Agriculture. Vol. 26 No.7 p July 1975 24

25 DISTRIBUSI AKAR TEBU & SERAPAN P
Akar tanaman tebu yang berfungsi menyerap hara terkonsentrasi di daerah bawah batang, tidak ada akar pada jarak lateral lebih dari 4 feet dari pusat barisan tanaman (kedalaman 6 inchi) . Konsentrasi tertinggi akar di sebelah sisi batang ditemukan pada kedalaman 3 inchi. Penyerapan fosfat oleh tanaman tebu ternyata berbanding langsung dengan pertumbuhannya. Terjadi penyerapan fosfat yang lambat tetapi mantap selama musim dingin dan musim semi. Sumber: Proceeding of the South African Sugar Technologist ‘s Association. April 1964 25

26 Sumber: Plant Physiology. Vol. 80, No. 1, Jan., 1986
P & TRANSPOR SUKROSE Transpor sukrose ke dalam vakuole sel tebu melibatkan sekelompok translokator. Translokator ini tergantung pada UDP-Glucose (Glc) eksternal, dan melalui serangkaian reaksi ensimatis di dalam tonoplast; sucrose phosphate dan sucrose diendapkan di dalam vesicles. Fructose-6-phosphate tidak duiperlukan untuk serapan UDP-Glc , dan juga tidak diserap. pH optimum untuk serapan UDP-Glc adalah Serapan UDP-Glc dihambat oleh para-chloromercuribenzene-sulfonic acid, UDP, dan GDP; carbonyl cyanide m-chlorophenylhydrazone juga sedikit menghambat . Sumber: Plant Physiology. Vol. 80, No. 1, Jan., 1986 26

27 EFEK RESIDU PUPUK P TANAMAN TEBU
Efek residual pupuk P p[ada hasil tebu dan kualitasnya ternyata cukup besar pada tanah cambisol dan vertisol. Kandungan P-tanah (residual) masih cukup tinggi, sehingga tebu tidak memerlukan pupuk P. The sugarcane varieties performed differently in terms of yield and quality under cambisol and vertisol. Performance was higher under cambisol soils than under vertisol soils, this was attributed to cambisol soils faster P release into the soil solution. Variety N14, KEN and EAK recorded yields higher than 90TCH and were of good quality under vertisol soils while varieties N14, KEN82-216, KEN82-472, KEN82-808, and KEN recorded yields higher than 100TCH under cambisol soils. This suggests variety N14, KEN and EAK may be efficient in P uptake in P fixing soils. The study concludes that P dynamics vary with soil types and therefore may influence P fertilizer management for sugarcane production. Sumber: 27

28 PENYERAPAN P TEBU A study was made of the effect of rainfall and of placement of fertilizer on fertilizer P uptake by sugar cane as measured by radioisotope methods. Placement tests were conducted with fertilizer applied in 2 bands 10 in, to the side of the row at depths of 6, 12 and 18 in. In one test fertilizer was applied in one band 4 in. below the stubble. It was found that rainfall during the 4-week period prior to sampling was closely correlated with fertilizer P uptake from the 6-in. depth but was not associated with uptake from the 12- and 18-in. depths. The correlation coefficients were r = 0.463, r = and r = , respectively. A negative correlation, r = , was observed between soil values for available P and yield response to fertilizer P. Correlation between means of the proportions of plant P from the fertilizer for all samplings at each site and yield response to fertilizer P at each site approached significance. Means of 8.8, 13.5 and 11.8 % of plant P from fertilizer P placed at the 6-in. depth were found at the 11, 15 and 19-week samplings, respectively. The mean uptake in the above-ground parts by the 19-week sampling was of P equivalent to 3.61 lb. of fertilizer P2O5per acre or 9.0% of the P applied. The rates of uptake of fertilizer P by sugar cane from the different depths suggest that roots develop vertically in greater number and activity early in the growing season than they do laterally. By the latter part of July the amounts of P uptake from the 6-, 12- and 18-in. depths were approximately equal. Placement of fertilizer in 2 vertical bands 6 in. in depth in the 6- to 12-in. zones 10 to 12 in. to the side of the row would permit feeding early in the growth period to be heavier in the lower portion of each band, and subsequent feeding in the entire band. -La St. Univ., Baton Rouge. Sumber: Conference proceedings; Book Proc. 12th Congr. int. Soc. Sugar Cane Technol., Puerto Rico, pp pp. 28

29 . 29

30 PEMUPUKAN P P dalam tanah tidak-mobil, therefore placement of phosphate fertilizers is a major management decision in crop production systems. No ideal special placement exists for all crops. Decisions about phosphate fertilizer placement depend on the intended crop, soil test P level, and environmental considerations. Phosphorus movement off agricultural land to surface waters can accelerate eutrophication. This is the process in bodies of water of stimulating algal growth which ultimately die and decay in the water, and deplete available oxygen. The reduced oxygen levels ultimately result in reduced higher-order aquatic plant and animal populations. Animal manures and bedding materials contain significant amounts of phosphorus in organic forms. After microbial mineralization from the organic forms, the phosphorus applied to soils is subject to the same fates as inorganic fertilizer phosphorus. Rates of land application of animal wastes such as poultry litter should be based on soil tests, nutrient content of the material, and crop needs. Directions on obtaining nutrient analysis of manures are available at your local Extension office. Phosphorus movement in landscapes is intmately associated with soil erosion because P is closely attached to solid soil materials. Phosphorus addition to soils must be managed to lessen movement to surface waters. Phosphorus needs of plants are most critical in the earliest growth stages. If the pH is between 6 and 7, and the soil has a low risk of erosion, P can be applied in the fall for cotton or grain production. 30

31 SERAPAN P TANAMAN Crop response to phosphorus depends on the availability of phosphorus in the soil solution and the ability of the crop to take up phosphorus. The availability of phosphorus in the soil solution has already been discussed. The ability of a plant to take up phosphorus is largely due to its root distribution relative to phosphorus location in soil. Because phosphorus is very immobile in the soil, it does not move very far in the soil to get to the roots. Diffusion to the root is only about 1/8 of an inch per year, and relatively little phosphorus in soil is within that distance of a root. Thus, the roots must grow through the soil and basically go get the phosphorus the plant needs. Therefore root growth is very important to phosphorus nutrition. Any factor that affects root growth will affect the ability of plant to explore more soil and get adequate phosphorus. Soil compaction, herbicide root injury, and insects feeding on roots can all dramatically reduce the ability of the plant to get adequate phosphorus. Young seedlings can suffer from phosphorus deficiency even in soils with high available phosphorus levels because they have very limited root systems that are growing very slowly in cold, wet, early early-season soil conditions. This is why some crops respond to phosphorus applied at planting in starter fertilizers even in relatively high phosphorus soils. 31

32 PERILAKU P DALAM TANAH The soil solution is the key to plant nutrition because all phosphorus that is taken up by plants comes from phosphorus dissolved in the soil solution. Because the amount of soluble phosphorus in the soil solution is very low, it must be replenished by as many as 500 times during a growing season to meet the nutritional needs of a typical crop. The bulk of the soil phosphorus is either in the soil organic matter or in the soil minerals. A large proportion of the phosphorus in both of these fractions is in very stable, unavailable forms, while a much smaller proportion is in available forms that can dissolve in the soil solution and be taken up by plants. The dynamic and available phosphorus phosphorus in these fractions, such as phosphorus added in fertilizer or manure, can be quickly fixed into stable, unavailable forms in the soil. This is why, even with optimum management, the efficiency of plant uptake of phosphorus is very low—usually less than 20 percent. At the same time as the soil solution phosphorus is depleted by crop uptake, unavailable phosphorus can slowly be released to more available forms to replenish the soil solution. This slow release can sustain plant growth in many natural systems, but is usually not rapid enough to maintain adequate phosphorus availability in intensively managed cropping systems without some supplemental phosphorus in the form of fertilizer, manure, or crop residues. 32

33 . Organic phosphorus availability depends on microbial activity to breakdown the organic matter and release this phosphorus into available forms. Thus, availability of organic phosphorus is very dependent on conditions in the soil and on the weather, which influence microbial activity. The mineralization of organic phosphorus to inorganic forms is favored by optimum soil pH and nutrient levels, good soil physical properties, and warm moist conditions. The inorganic phosphorus is bound with varying adhesiveness to iron and aluminum compounds in the soil. Replenishment of the soil solution with phosphate from inorganic forms comes from slow dissolution of these minerals. The solubilities of the compounds holding phosphorus are directly related to the soil pH. The pH range of greatest phosphorus availability is 6.0 to 7.0. At a lower pH, when the soil is very acidic, more iron and aluminum are available to form insoluble phosphate compounds and, therefore, less phosphate is available. At very high pH, phosphorus can react with excess calcium to also form unavailable compounds in the soil. 33

34 Phosphate is largely immobile in soil and must be placed close to the roots to be beneficial to a plant. Since phosphate often binds to the soil and does not get to the roots for uptake, many applications of granular phosphate are wasted. 34

35 Korelasi terbaik terjadi pada luas permukaan akar.
CIRI-CIRI AKAR TEBU Serapan hara N, P, K, Ca, Mg, Si dan S dipengaruhi oleh sifat-sifat akar tebu seperti bobot akar, luas permukaan akar, KTK, dan KTA. Dalam tanah dan kultur larutan, KTK dan KTA akar tebu tidak berkorelasi dengan jumlah serapan kation dan anion; hal ini mungkin disebabkan oleh karena serapan ion terjadi melalui proses aktif, bukan melalui pertukaran ion. Dalam kultur larutan, bobot akar, luas permukaan akar, KTK dan KTA-akar tanaman tebu berkorelasi dengan bobot batang dan serapan hara N, K, Ca, Mg dan S. Korelasi terbaik terjadi pada luas permukaan akar. Dalam kultur tanah, hanya bobot akar yang berkorelasi erat dengan bobot batang dan serapan hara N, Mg dan S. SUmber: Journal of the Science of Food and Agriculture. Vol. 26 No.7 p July 1975 35

36 DISTRIBUSI AKAR TEBU & SERAPAN P
Akar tanaman tebu yang berfungsi menyerap hara terkonsentrasi di daerah bawah batang, tidak ada akar pada jarak lateral lebih dari 4 feet dari pusat barisan tanaman (kedalaman 6 inchi) . Konsentrasi tertinggi akar di sebelah sisi batang ditemukan pada kedalaman 3 inchi. Penyerapan fosfat oleh tanaman tebu ternyata berbanding langsung dengan pertumbuhannya. Terjadi penyerapan fosfat yang lambat tetapi mantap selama musim dingin dan musim semi. Sumber: Proceeding of the South African Sugar Technologist ‘s Association. April 1964 36

37 Sumber: Plant Physiology. Vol. 80, No. 1, Jan., 1986
P & TRANSPOR SUKROSE Transpor sukrose ke dalam vakuole sel tebu melibatkan sekelompok translokator. Translokator ini tergantung pada UDP-Glucose (Glc) eksternal, dan melalui serangkaian reaksi ensimatis di dalam tonoplast; sucrose phosphate dan sucrose diendapkan di dalam vesicles. Fructose-6-phosphate tidak duiperlukan untuk serapan UDP-Glc , dan juga tidak diserap. pH optimum untuk serapan UDP-Glc adalah Serapan UDP-Glc dihambat oleh para-chloromercuribenzene-sulfonic acid, UDP, dan GDP; carbonyl cyanide m-chlorophenylhydrazone juga sedikit menghambat . Sumber: Plant Physiology. Vol. 80, No. 1, Jan., 1986 37

38 EFEK RESIDU PUPUK P TANAMAN TEBU
Efek residual pupuk P p[ada hasil tebu dan kualitasnya ternyata cukup besar pada tanah cambisol dan vertisol. Kandungan P-tanah (residual) masih cukup tinggi, sehingga tebu tidak memerlukan pupuk P. The sugarcane varieties performed differently in terms of yield and quality under cambisol and vertisol. Performance was higher under cambisol soils than under vertisol soils, this was attributed to cambisol soils faster P release into the soil solution. Variety N14, KEN and EAK recorded yields higher than 90TCH and were of good quality under vertisol soils while varieties N14, KEN82-216, KEN82-472, KEN82-808, and KEN recorded yields higher than 100TCH under cambisol soils. This suggests variety N14, KEN and EAK may be efficient in P uptake in P fixing soils. The study concludes that P dynamics vary with soil types and therefore may influence P fertilizer management for sugarcane production. Sumber: 38

39 ASAM HUMAT & EFISIENSI PUPUK P
Percobaan inkubasi dilakukan untuk memantau perubahan kandungan P-ekstraks bikarbonat , sebagai akibat dari perlakuan pupuk SSP yang dikombinasikan dengan FYM dan asam humat. Tanah berkapur diinkubasi dengan SSP (60 kg ha-1) yang dikombinasikan dengan FYM dan asam humat (200, 400, 800, 1600 dan 2000 gms ha-1). Aplikasi pupuk kompos FYM tidak berpengatruh terhadap mineralisasi P–pupuk, diduga hal ini karena dosisnya kurang banyak. Asam humat (batubara lignitik) dengan dosis 200 g ha-1 menunjukkan imobilisasi-P paling sedikit, baik P-alami maupun P-pupuk selama inkubasi 16 minggu. Persen recovery P dan P-mineralisasi lebih besar pada perlakuan asam humat dengan dosis 200 g ha-1. Sumber: Journal of Agricultural and Biological Science. VOL.1, NO.1, JULY 2006 39

40 . INFLUENCE OF RESDIUAL PHOSPHORUS ON YIELD AND QALITY OF SUGARCANE
P. Ochola and J.O. Omollo KESREF The effect of residual phosphorus (P) on yield and quality of six sugarcane varieties, N14, KEN82-216, KEN , KEN82-808, KEN and EAK was evaluated in cambisol and vertisol soils, located at the experimental fields of KESREF-Kibos. This followed soil test in these fields which revealed high P levels and therefore P fertilizer may not be required for sugarcane growth. Sugarcane was planted without P fertilizer unlike the recommendation where P fertilizer is applied. The sugarcane varieties performed differently in terms of yield and quality under cambisol and vertisol. Performance was higher under cambisol soils than under vertisol soils, this was attributed to cambisol soils faster P release into the soil solution. Variety N14, KEN and EAK recorded yields higher than 90TCH and were of good quality under vertisol soils while varieties N14, KEN82-216, KEN82-472, KEN82-808, and KEN recorded yields higher than 100TCH under cambisol soils. This suggests variety N14, KEN and EAK may be efficient in P uptake in P fixing soils. The study concludes that P dynamics vary with soil types and therefore may influence P fertilizer management for sugarcane production. Diunduh dari: 40

41 . INFLUENCE OF RESDIUAL PHOSPHORUS ON YIELD AND QALITY OF SUGARCANE
P. Ochola and J.O. Omollo KESREF . Sugarcane performance depends on availability of major nutrients in the soil among other factors. One such major nutrient is phosphorus (P) which is the third most commonly limiting nutrient after water and nitrogen (Malavolta, 1994). Phosphorus plays an important role in sugarcane germination and early stages of growth generally referred to as sugarcane establishment. P role in sugarcane is for root and primary shoots development, tillering and stalks elongation (Blackburn, 1984). It also promotes sucrose synthesis and accumulation (Blackburn, 1984). Phosphorus deficiency results in reduced metabolic rate and photosynthesis leading to reduced yield and quality. This is undesirable as it could lead to a fall in sugarcane productivity. Phosphorus occurs in soil in both inorganic and organic forms. The concentration of the inorganic forms in the soil solution is the most important factor governing the availability of this element to plants. Phosphate equilibrium in the soil system is; -non labile P labile P solution P plant root uptake (Black, 1993; Tisdale et al, 1993;. Black, C.A. (1993). Soil Fertility Evaluation and Control. Lewis Publishers, Boca Raton, Florida. Blackburn, F. (1984). Sugarcane. Longman, Harlow Malavolta, E. (1994). Fertilizing for High Yield Sugarcane. International Potash Institute. Basel. Tisdale, S.L., Nelson, W.L., Beaton, J.D. and Halvin, J.L. (1993). Soil Fertility and Fertilizers. 5th Edition. MacMillan, New York. Diunduh dari: 41

42 INFLUENCE OF RESDIUAL PHOSPHORUS ON YIELD AND QALITY OF SUGARCANE
P. Ochola and J.O. Omollo KESREF Soil condition with regard to soil pH affects the dynamics of P. Acid soils below pH of 6.0 and alkaline soils above pH of 8.0 increase P fixation and hence unavailability to the soil solution for plant uptake (Landon, 1991; Tisdale et al. 1993; Brady, 2000). Soil types rich in 1:1 clay minerals are rich in sesquioxides and high Al oxides which increases P fixation unlike clay rich in 2:1 clay minerals (Landon, 1991). It is therefore imperative to understand the soil types and possible dynamics of P for judicious P fertilizer use in sugarcane cropping. However, this has not been the case and therefore application P in cane fields during planting has been the normal practice. The recommended application rate has been 40 – 60 kgP2O5/ha recommended for the zone (KESREF, 2002). In reviewing the rate, soil tests were carried out to determine the available P levels among other soil chemical properties. The tests revealed high P levels of more than 25 ppm in the major soil types, vertisol and cambisol. These soil types have different characteristics which influence the retention and release of P for plant uptake. Kenya Sugar Research Foundation (2002). Sugarcane Grower’s Guide. Kisumu. Landon, J.R. (1991). Booker Tropical Soil Manual. A Handbook for soil survey and agricultural land evaluation in the tropics and subtropics. Longman, New York. Diunduh dari: 42

43 . INFLUENCE OF RESDIUAL PHOSPHORUS ON YIELD AND QALITY OF SUGARCANE
P. Ochola and J.O. Omollo KESREF Conclusion Sugarcane varieties varied in performance under the cambisol and vertisol soils. This was attributed to the soil chemical characteristics of the soil types. The vertisol and cambisol fix phosphorus but the P release intensity may vary. Cambisol soil releases P much faster than the vertisol soils. The P released into the soil solution is taken up by sugarcane, hence better performance in cambisols than in vertisols when no P fertilizer is applied. Despite high P levels in vertisol soils, P fertilizer use may be required subject to fertilizer use evaluation. Methods of evaluating fertilizer use for sugarcane such as foliar testing, field trials should complement the soil testing method so as to appropriately determine fertilizer use. KEN and EAK performed well under vertisol soils and are therefore tolerant to unavailable P. Varieties KEN82-216, KEN and KEN yielded below 90TCH under vertisols but above 100TCH under cambisols. This suggests they may be sensitive to low P and will therefore require P application for increased yields. Diunduh dari: 43

44 Sources of phosphorus for sugar cane (1961-63).
ALVAREZ, . et al. Sources of phosphorus for sugar cane ( ). Bragantia [online]. 1965, vol.24, n.unico, pp ISSN   Five experiments were conducted in the State of São Paulo to study the efficiency of different sources of phosphorus for the production of sugar cane on three types of soil, using 50, 100 and 150 kilograms of total P2O5 per hectare in the presence of NK. The soil pH varied from 4.8 to 5.6. Phosphorus significantly increased the yields in all of the experiments. As an average of the five experiments and the three rates of application, the per-cent yield increases caused by the studied phosphorus carriers were the following: thermophosphate, 49; dicalcium phosphate, 39; bone meal, 38; ordinary superphosphate, 35; Alvorada-phosphate, 28; Olinda-phosphate, 26; Araxá-phosphate, 20; phosphorous bauxite, 10. The four latter sources are natural phosphates from different regions of Brazil. Diunduh dari: ………. 44

45 Sugarcane Response to Phosphorus Fertilizer on Everglades Histosols
McCray JMabry, Rice RonaldW, Luo Yigang, Ji Shangning Agronomy Journal [2010, 102(5): ] Determining sugarcane (Saccharum spp.) yield response to P fertilizer supports the development of agricultural best management practices consistent with Everglades restoration efforts. Field studies were conducted on organic soils to determine sugarcane yield responses to P fertilizer. Four test sites were established on Florida Histosols (water-extractable P = 1.3, 1.7, 2.1, and 9.0 g P m−3) with annual banded rates of 0, 9, 18, 36, 72, and 144 kg P ha−1 There were a total of 13 crop years with duration of each test ranging from 2 to 4 yr. Linear and quadratic regression and single degree of freedom contrasts were used to determine P fertilizer requirements. There were responses in t cane ha−1 (TCH) and t sucrose ha−1 (TSH) to P fertilizer application at four and three sites, respectively. Annual fertilizer P requirement at the four sites ranged from 18 to 33 kg P ha−1, with no consistent change in P requirement across crop years. Based on measured response (95% of maximum yield) in TCH and TSH up to 33 kg P ha−1, the maximum P recommendation for sugarcane grown on Florida Histosols should be maintained at 36 kg P ha−1 Minimal reductions in sucrose concentration (kg sucrose t−1 cane) were measured at P rates ≤36 kg P ha−1 Water-extractable P did not predict the measured yield response at all sites, demonstrating the need for an updated soil test calibration that should be applicable over a wide pH range and include both quickly available and reserve soil P. Diunduh dari: ………. 45

46 American Society of Agronomy Abstracts. CDR. S02-daroub154631-Oral.
Daroub, S., Glaz, B.S., Morris, D.R Phosphorus availability to sugarcane in histosols under periodic flooding. American Society of Agronomy Abstracts. CDR. S02-daroub Oral. Subsidence of organic soils and phosphorus (P) release into surface water are two major issues facing agriculture in the Everglades Agricultural Area in south Florida. Raising the water table depth and periodic flooding may reduce the rate of oxidation of these soils. This study was conducted to quantify changes of P in both soil and water during periodic flooding and draining cycles in an organic soil under sugarcane production. The effect of five cycles of periodic flooding (for 1 week) and draining (for 14 days) while maintaining the water table depth at 16, 33, and 50 cm was compared to a continuous water table depth of 50 cm. Periodic flooding cycles did not have a major effect on P availability. Microbial P significantly increased in all treatments with time. Acetic acid extractable P was higher in only 6 out of the 25 extraction dates in the flood and 16 cm treatment compared to the continuous 50 cm water table depth. There were no significant increases in P in canal water as a result of periodic flooding. This study does not support previous column studies that show increased release of P from organic soils under flood-drain cycles. Diunduh dari: ………. 46

47 McCray, J. Mabry; Rice, Ronald W.; Luo, Yigang; Ji, Shangning
Phosphorus Fertilizer Calibration for Sugarcane on Everglades Histosols McCray, J. Mabry; Rice, Ronald W.; Luo, Yigang; Ji, Shangning Communications in Soil Science and Plant Analysis, Volume 43, Number 20, 1 November 2012 , pp (17) A calibrated soil test for phosphorus (P) fertilizer application to sugarcane (Saccharum spp.) grown on organic soils in southern Florida is an important best-management practice for minimizing P loads in water draining to the Everglades. The current calibration uses water as the soil extractant, which has the limitations of being very sensitive to pH and being most applicable to short-season crops. Phosphorus fertilizer rate studies at six locations (20 total crop years) were analyzed to develop an updated soil-test P calibration for sugarcane on organic soils. Phosphorus extracted with water, acetic acid, and Bray 2 did not consistently relate well to crop response. A new P soil-test calibration for sugarcane is proposed based on Mehlich 3 soil extraction, with a maximum rate of 36 kg P ha−1 with ≤ 10 g P m−3 in preplant soil samples and no P recommended with >30 g P m−3. Diunduh dari: ………. 47

48 S. K. de Datta and J. C. Moomaw
Availability of Phosphorus to Sugar Cane in Hawaii as Influenced by Various Phosphorus Fertilizers and Methods of Application S. K. de Datta and J. C. Moomaw Experimental Agriculture / Volume 1 / Issue 04 / October 1965, pp An experiment was carried out in the glasshouse to determine the availability of P, and utilization of added phosphate fertilizers from three fertilizer materials, applied by two different methods to sugar cane grown in four diverse soil systems. Phosphorus was applied at the equivalent rate of 175 pounds P (400 pounds P2O5) per acre. A larger response from added P in terms of plant yields was obtained from an aluminous ferruginous latosol and least from dark magnesium clay. Differences in yields of sugar cane were evidently associated with differences in P content in the cane plants and, in certain cases, with a reduction in Al content in plant tops, and the less soluble superphosphate increased yields more than the highly soluble NH4H2PO4. Phosphate fertilizers applied as foliar spray greatly increased the P content in the plants, and plants contained twenty times more P when sprayed with NH4H2PO4 than when the same fertilizer was applied to the soil. However, increased P content in the plants did not necessarily indicate that the P was translocated within the plants or that the added P participated in metabolic processes. The evidence indicated that in soils where the ‘A’ value was high the P status of the sugar cane tops was not correspondingly high. Diunduh dari: ………. 48

49 Phosphorus efficiency of sugarcane varieties in a tropical alfisol
Fertilizer research. 1994, Volume 39, Issue 2, pp 83-88 Phosphorus efficiency of sugarcane varieties in a tropical alfisol B. Sundara Varietal differences in P absorption and utilization by sugarcane were studied with the objective of selecting phosphorus efficient varieties which can perform well under conditions of low soil phosphorus availability and at low P application rates. Sugarcane varieties differed significantly in dry matter, cane and sugar yields, P-concentration and P-uptake. Based on the cane and sugar yield phosphorus efficiency indices, varieties were classified as ‘P efficient’ and ‘P-non-efficient’. Phosphorus efficient varieties had low P-concentrations and produced higher dry matter per unit P absorbed. Diunduh dari: 49

50 Ismail, A. M. A.; Hagrus, A. M.; El-Sonbaty, M. M.; Farrag, S. H.
Effect of phosphobacterin and phosphorus levels on yield and quality of sugarcane. Ismail, A. M. A.; Hagrus, A. M.; El-Sonbaty, M. M.; Farrag, S. H. Journal Egyptian Journal of Agricultural Research 2000 Vol. 78 No. 4 pp Two field trials were carried out at Mattana Agricultural Research Station (Qena Governorate), Egypt, in two growing seasons ( and ) to study the effect of phosphorus fertilizer and phosphobacterin (biofertilizer) on growth, juice quality and yield of sugarcane. The trial consisted of twenty-four treatments which were the combinations between six levels of phosphorus fertilization (0, 15, 30, 45, 60 and 75 kg P2O5/fed) which were allocated at random in the main plots and four levels of phosphobacterin (0, 250, 500 and 750 g Pb/fed) which were randomly distributed in the sub plots. A split plot design with four replications was used. The plot size was 35 m2. Variety G. 85/37 was planted. The obtained results indicated that phosphorus levels had a significant influence on purity percentage while their effect on the length and diameter of stalks, sucrose percentage, cane and sugar yields were insignificant. The best level of phosphorus fertilization was 60 kg P2O5/fed. Phosphobacterin levels significantly affected stalk length, sucrose percentage, cane and sugar yields. Mostly, applying 500 g Pb/fed gave the highest value for the previous characters. The interaction between phosphorus and phosphobacterin levels did not significantly affect all the studied attributes. Diunduh dari: 50

51 Phosphorus use efficiency of sugarcane varieties
Fernando Cesar Bachiega Zambrosi Instituto Agronômico (IAC). Agência Paulista de Tecnologia dos Agronegócios (APTA). Secretaria de Agricultura e Abastecimento (São Paulo - Estado). Campinas, SP, Brazil January 01, December 31, 2013 The research with regard to phosphorus (P) management in the sugarcane is a very important issue due to widespread occurrence of low-P soils. We are proposing a study with the objectives of: i) characterize the variability in the efficiency of P uptake and utilization of sugarcane varieties; ii) determine features related to distinct P use efficiency among sugarcane varieties; iii) evaluate the responses of different varieties to low-P availability in the soil and iv) effect of P supply and variety on the shoot regrowth. The varieties IAC , IACSP , IAC , RB867515, IACSP and IACSP will be subjected to P deficient (P rate = 40 mg kg-1 of soil) and P sufficient (P rate = 400 mg kg-1 of soil) treatments. Plant growth, total P uptake, P fractioning and acid phosphatase activity in the leaves will be determined. Before harvesting the experiment, leaf gas exchange and photochemical activity will be evaluated in mature leaves. Total dry weight and P accumulated by the plants will be used to obtain P uptake, utilization and use efficiency. We expect that our results can contribute to define sugarcane varieties more efficient in P use and to characterize the responses of sugarcane related to the adaptation to low-P availability. Therefore, our research purpose might lead to improved understanding of sugarcane P nutrition and P management in low-P soils. Diunduh dari: 51

52 Phosphorus nutrition of sugarcane: growth, yield and quality of ratoon cane as affected by residual soil phosphorus. Matin, M. A.; Oya, K.; Shinjo, T.; Horiguchi, T. Japanese Journal of Tropical Agriculture 1997 Vol. 41 No. 3 pp The residual effects of soil P on the growth, yield and quality of ratoon sugarcane were investigated in a Dark Red soil of Okinawa, Japan, with cv. F-177. The residual soil P levels after harvest of canes were 5.6, 9.1, 11.6 and 15.9 mg available P2O5/100 g soil denoted as A, B, C and D levels, respectively. Leaf area index, dry matter production and root biomass increased for the B, C and D levels of soil P compared with the A level. About 62-67% of the total dry matter was produced between 120 and 240 DAR which corresponds to the period of most rapid growth of ratoon cane under all soil P levels. Higher residual soil P (B, C and D levels) significantly increased the millable cane number compared with the lower residual soil P (A level). The highest ratoon cane yield was obtained in the D plot (125 tons/ha) followed by the C plot (122 tons) and the sugar yield increased by 48% in the D plot and 46% in the C plot compared with the A plot (12 tons). Leaf nutrient contents were influenced by the level of soil P. Lower leaf N content accompanied with higher P at the mature stage showed a positive relationship with the sugar yield. Furthermore, the Zn and Cu contents in leaf were adversely affected by the higher P soil compared with the lower P soil. Although the highest cane and sugar yield was obtained in the D plot followed by the C plot compared with the other plots, the differences in cane and sugar yield between the C and D plots were not statistically significant. Diunduh dari: 52

53 Y. J. Zhu, E. Komor and P. H. Moore
Sucrose Accumulation in the Sugarcane Stem Is Regulated by the Difference between the Activities of Soluble Acid Invertase and Sucrose Phosphate Synthase Y. J. Zhu, E. Komor and P. H. Moore Plant Physiology October 1997 vol. 115 no To assess the relative importance of morphological and biochemical factors in the regulation of sucrose (Suc) accumulation in the sugarcane (Saccharum spp. hybrids) stem, we investigated morphological and biochemical correlates of Suc accumulation among parents and progeny of a family segregating for differences. In contrast to the parents, no relationship was observed between morphology and the level of Suc accumulation among the progeny. The level and timing of Suc accumulation in the whole stalk and within individual internodes was correlated with the down-regulation of soluble acid invertase (SAI) activity. High SAI activity prevented most, but not all, Suc accumulation. There was a critical threshold of SAI activity above which high concentrations of Suc did not accumulate. This low level of SAI activity was always exceeded in the internodes of the lower-Suc-storing genotypes. However, low activity of SAI was not sufficient by itself to account for the Suc accumulation in the higher-Suc-storing genotypes. Major differences in Suc accumulation among the population were attributed to the difference between activities of SAI and Suc phosphate synthase, provided SAI is below the critical threshold concentration. This result is not unexpected, since the pathway of Suc transport for storage involves Suc hydrolysis and resynthesis. Diunduh dari: 53

54 Journal of Agricultural and Food Chemistry [2011, 59(5):1829-1836]
Improved sugar cane juice clarification by understanding calcium oxide-phosphate-sucrose systems. Doherty WO Journal of Agricultural and Food Chemistry [2011, 59(5): ] It is accepted that the efficiency of sugar cane clarification is closely linked with sugar juice composition (including suspended or insoluble impurities), the inorganic phosphate content, the liming condition and type, and the interactions between the juice components. These interactions are not well understood, particularly those between calcium, phosphate, and sucrose in sugar cane juice. Studies have been conducted on calcium oxide (CaO)/phosphate/sucrose systems in both synthetic and factory juices to provide further information on the defecation process (i.e., simple liming to effect impurity removal) and to identify an effective clarification process that would result in reduced scaling of sugar factory evaporators, pans, and centrifugals. Results have shown that a two-stage process involving the addition of lime saccharate to a set juice pH followed by the addition of sodium hydroxide to a final juice pH or a similar two-stage process where the order of addition of the alkalis is reversed prior to clarification reduces the impurity loading of the clarified juice compared to that of the clarified juice obtained by the conventional defecation process. The treatment process showed reductions in CaO (27% to 50%) and MgO (up to 20%) in clarified juices with no apparent loss in juice clarity or increase in residence time of the mud particles compared to those in the conventional process. There was also a reduction in the SiO2 content. However, the disadvantage of this process is the significant increase in the Na2O content. Diunduh dari: 54

55 PENTINGNYA FOSFAT BAGI PERTANAMAN TEBU
Foto: smno.kampus.ub.agst2012 55